Epistasis effects and inheritance of harvest index, drought and heat-resistance related traits in groundnut (Arachis hypogaea L.)

Abstract

Improved water-use efficiency coupled with heat stress tolerance and high harvest index (HI) are the suggested selection criteria for breeding groundnut varieties with high yield under drought stress. Genetic control of HI, and traits related to drought and heat resistance was studied following a triple test cross mating design. The experimental materials consisting of 27 progenies produced by crossing nine inbred lines belonging to both Spanish and Virginia botanical groups with three testers (TAG 24, TMV 2 NLM, and their F1) were evaluated in a replicated trial. The data on parents, F1s and three-way crosses were analysed for HI, specific leaf area (SLA), soil and plant analytical device chlorophyll meter reading (SCMR), carbon isotope discrimination (Δ13C) and relative cell injury (RCI). The inheritance pattern revealed importance of epistasis in the manifestation of all the five traits. Partitioning of total epistasis to its component parts detected additive × additive (i) type epistasis for HI, and additive × dominance (j) + dominance × dominance (l) type for Δ13C, however, for SCMR and RCI both i and j+l types of epistasis were important with the preponderance of the former. In two lines (JL 24 and PBS 12160), epistatic deviations were observed for SLA also when these were detected with the t-test. The findings suggest that genetic gains for HI and resistance to drought and heat stress can be achieved by conventional breeding through selection for their related traits. It would be necessary to delay the selection process until maximum frequency of homozygous loci is achieved to exploit i-type epistasis